Thrall is a city in Williamson County, Texas, United States. Its population was 816 at the 2020 census. The name Thrall was chosen by the co…Thrall is a city in Williamson County, Texas, United States. Its population was 816 at the 2020 census. The name Thrall was chosen by the community to honor the Rev. Homer S. Thrall, a Methodist minister and historian much admired by local settlers and residents. Thrall was founded in 1876.